Tilt compensation for tremor cancellation device

ABSTRACT

A method of tremor reduction in a handheld device includes measuring a tremor motion and a tilt motion with a motion tracking module (“MTM”) disposed in a housing of the handheld device. In response to measuring the tremor motion, an attachment arm is moved with at least one motion generating mechanism to reduce the tremor motion in the attachment arm. Additionally, in response to measuring the tilt motion, the attachment arm is moved with the at least one motion generating mechanism to resist the attachment arm hitting a hard stop in the handheld device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/745,270, filed Jan. 16, 2020, which is a continuation of U.S. patentapplication Ser. No. 15/257,111, filed Sep. 6, 2016, the contents ofwhich are incorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates generally to unintentional muscle movements, andin particular but not exclusively, relates to stabilizing a handheldtool while it is being used by the user.

BACKGROUND INFORMATION

Movement disorders are often caused by chronic neurodegenerativediseases such as Parkinson's Disease (“PD”) and Essential Tremor (“ET”).Both of these conditions are currently incurable and cause unintentionalmuscle movements or human tremors—uncontrollable rhythmic oscillatorymovements of the human body. In many cases human tremors can be severeenough to cause a significant degradation in quality of life,interfering with daily activities/tasks such as eating, drinking, orwriting.

Currently, persons with chronic neurodegenerative diseases are typicallymedicated with drugs that vary in effectiveness. The alternative topharmacological treatment is brain surgery, such as deep brainstimulation (DBS) surgery. Similar to pharmacological treatments, DBSsurgery varies in its effectiveness while being invasive and dangerous.Both forms of treatment are therefore non-optimal for treating personswith chronic neurodegenerative diseases, especially with respect toperforming daily activities.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles beingdescribed.

FIG. 1A illustrates a handheld tool that tracks unintentional musclemovements and performs motion stabilization, in accordance with anembodiment of the disclosure.

FIG. 1B illustrates the handheld tool of FIG. 1 and further showsattachment/detachment functionality, in accordance with an embodiment ofthe disclosure.

FIG. 1C illustrates the handheld tool of FIG. 1 along with one exampleof a hard-stop, in accordance with an embodiment of the disclosure.

FIGS. 2A-2C illustrate a variety of handheld tool attachments, inaccordance with several embodiments of the disclosure.

FIG. 3 is a flowchart illustrating a method of tremor stabilization andhard stop resistance, in accordance with several embodiments of thedisclosure.

DETAILED DESCRIPTION

Embodiments of an apparatus and method for tilt compensation for atremor cancelation device are described herein. In the followingdescription numerous specific details are set forth to provide athorough understanding of the embodiments. One skilled in the relevantart will recognize, however, that the techniques described herein can bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring certain aspects.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Handheld devices may be used to counteract tremor resulting fromParkinson's or other diseases. For example, a handheld device with aspoon attachment may allow a person with Parkinson's to eat normally bystabilizing the spoon end of the device so that food stays on the spoon.While the handheld device may effectively counter tremor motion byfiltering high-frequency motions, it may not respond well to tilt(low-frequency) motions that result from the attachment end of thedevice being pulled by gravity. These tilt motions may result in theattachment end of the device hitting a hard stop. In the spoon example,if the attachment end of the device hits a hard stop (e.g., theoutermost point of its range of motion) the food on the spoon may bethrown off of the spoon. In other words, tilting the device side to sidemy result in the spoon attachment falling against one of the device'shard stops. Accordingly, systems and methods here both mitigate tremormotions in handheld devices and also prevent low frequency tilt motionsfrom limiting usability.

FIG. 1A illustrates a handheld tool 100 that tracks unintentional musclemovements and performs motion stabilization, in accordance with anembodiment of the disclosure. Handheld tool 100 is capable of detectingand compensating for unintentional high frequency muscle movement (e.g.,tremors) and low frequency motions (e.g., tilts). In one embodiment, themuscle movements are high frequency when they occur in a range ofapproximately 1-2 centimeters about a central point of handheld tool100, although unintentional high frequency muscle movements may be aslarge as 8-10 centimeters about a central point of handheld tool 100. Inthe embodiments discussed herein, handheld tool 100 tracks theseunintentional high frequency muscle movements, and stabilizes a positionof attachment arm 104 in spite of the unintentional muscle movementswhile implement 102 is being used by a user. Moreover, circuitry inhandheld tool 100 may detect when handheld tool 100 is being slowlytilted, and may prevent attachment arm 104 from hitting one of thesidewalls causing a hard stop.

Accordingly, the illustrated embodiment of handheld tool 100 includesmotion tracking module (“MTM”) 120 for measuring and tracking usertremors as well as low frequency tilt motions. In one embodiment,handheld tool 100 includes two or more sensors (e.g., sensor 122 and124) for providing signals to MTM 120 for compensating for tremors andtilt motions, as discussed herein. These subsystems may have distinctcomponents, or share some components such as power systems, memory, andmay even share one or more sensors.

Handheld tool 100 includes housing 106, which functions as a handleenabling a user to hold handheld tool 100. As stated, handheld tool 100also includes attachment arm 104 coupled to housing 106 via motiongenerating mechanisms, as discussed in greater detail below. Attachmentarm 104 is configured to accept an attachment 102 (e.g., auser-assistive device, such as a spoon, fork, toothbrush, paintbrush, orthe like) to its end distal from housing 106. In one embodiment,attachment arm 104 is integrated with a specific type of implement 102(e.g., the spoon as illustrated). In other embodiments, attachment arm104 can receive a variety of different implements 102 in a variety ofways including but not limited to friction hold, snap clasp, magnet,screw, or other form of locking mechanism (see e.g., FIGS. 1B and2A-2C).

The depicted embodiment of handheld tool 100 includes motion trackingmodule 120 for measuring and tracking tremors, such as unintentionalhigh frequency muscle movements of a user, as well as for controllingstabilization performed by handheld tool 100 using a first motiongenerating mechanism (e.g., first actuator 108, first gear reductionunit 110, and first gearing unit 112) and a second motion generatingmechanism (e.g., second actuator 130, second gear reduction unit 132,and second gearing unit 134), discussed in greater detail below. In oneor more embodiments, first actuator 108 and second actuator 130 mayinclude motors. One skilled in the art will appreciate that while thedepicted embodiment has two motion generating mechanisms otherembodiments may have one or more than two. In several embodiments,attachment arm 104 is coupled with housing 106 via the coupling of thefirst motion generating mechanism with the second motion generatingmechanism. Furthermore, one or more components of MTM 120 are rigidlyattached to housing 106 to measure and track tremors of the handle thatthe user holds. FIG. 1A illustrates MTM 120 as a single component withinhousing 106; however, in other embodiments, MTM 120 includes severalfunctional items that may assume a variety of different form factors andmay further be spread throughout housing 106, such as within attachmentarm 104. In one embodiment, MTM 120 includes at least one gyroscope, andthe at least one gyroscope is located in at least one of a distal end ofattachment arm 104 or anywhere in the housing 106.

The illustrated embodiment of handheld tool 100 further includes atleast two motion sensors (e.g., a first motion sensor 122 placed alongor within body and a second motion sensor 124 placed along or withinattachment arm 104). The motion sensors 122 and 124 respectively measuremovements of housing 106 and attachment arm 104, to enable MTM 120 todetermine movements of housing 106 and attachment arm 104 relative toone another. The sensor 122 sends motion signals back to MTM 120 so thatMTM 120 can determine, in real time or near real time, direction, speed,and magnitude of unintentional high frequency muscle movements of a userusing handheld tool 100. These measured movements are provided to MTM120 to enable a controller disposed in MTM 120 to provide motion signalsthat drive the first and second motion generating mechanisms tostabilize the implement 102 despite the user's unintentional highfrequency muscle movements. In one embodiment, the motion sensors 122and 124 are sensors including, but not limited to, one or more of anaccelerometer, gyroscope, or combination of the two. In anotherembodiment, each of motion sensor 122 and 124 is a inertial measuringunit.

Handheld tool 100 further includes a portable power source 140 to powerthe MTM 120, actuator 108, and actuator 130. The portable power source140 can include one or more rechargeable batteries. In embodiments, therechargeable batteries of portable power source 140 may be recharged viacharging interface 142 to a charging power source, where charginginterface 142 couples portable power source 140 to the charging powersource via an indicative, wired, or other form of connection.Furthermore, power source 140 may utilize other options including butnot limited to a solar panel, primary batteries, etc.

In one embodiment, the first motion sensor 122 and second motion sensor124 are inertial motion sensors respectively distributed in housing 106and attachment arm 104. In one embodiment, the first motion sensor 122is responsible for measuring movements of the housing 106 and the secondmotion sensor 124 is responsible for measuring movements of theattachment arm 104. The first and second motion sensors 122 and 124provide motion signals, indicative of the measured movements, to MTM 120for determining the motion of the housing 106 as well as the relativemotions of the housing 106 and the attachment arm 104. In embodiments,one or more of the components for tracking tremor motions and/orperforming tilt stabilization may be omitted and/or positions of sensorschanged while still implementing the tremor tracking and tiltstabilization functionality disclosed herein. As examples, rotaryencoders, potentiometers, or other position tracking devices placed onthe joints of movement of the handheld tool 100, and a single motionsensor can be employed either in the tip (e.g., attachment arm 104 orimplement 102) or housing 106. In these embodiments, the combination ofsensors and placement on handheld tool 100 enable MTM 120 to infer(through device kinematics) where attachment arm 104 and housing 106are, and their positions relative to each other, for tremor tracking andtilt compensation purposes.

The first motion sensor 122 and second motion sensor 124 detectunintentional muscle movements and measure signals related to theseunintentional muscle movements that are created when a user adverselyaffects motion of implement 102 (e.g., as a result of unintentional highfrequency muscle movements). These sensors also detect the motion of thestabilized output relative to the housing 106. In one embodiment, thefirst motion sensor 122 detects movements of the housing 106, althoughsensor 124 could also be used for detecting movements of the housing106. Furthermore, the combined measurements of the sensors 122 and 124enable movements of the housing 106 and implement 102 relative to oneanother to also be detected. The controller coupled to, or included in,MTM 120 sends voltage commands in response to the detected motions to atleast one of actuator 108 and actuator 130. The voltage commands arechosen by the controller to generate a complementary motion to thedetected motions of housing 106. In one embodiment, the complementarymotion is a positioning of attachment arm 104 upon jointly drivingactuator 108 and actuator 130 to stabilize implement 102 (e.g., maintainimplement 102 in a centered position relative to the user's tremors orunintentional muscle movements effecting motion of the housing 106). Thevoltage commands drive one or more of actuator 108 and actuator 130 togenerate motion of the attachment arm 104 and therefore the implement102 in a direction opposite to the detected user motions. Furthermore,the voltage commands further drive one or more of actuator 108 andactuator 130 to generate a motion of equal magnitude of the detecteduser motion. The voltage commands from the controller in MTM 120therefore control motion of the implement 102 by jointly driving themotion generating mechanisms to cancel out the user's unintentional highfrequency motion thereby stabilizing the implement 102 relative tomotion of the housing 106 by a user.

Further the controller in MTM 120 may, in response to MTM 120 detectinga tilt motion, control the at least one motion generating mechanism toresist attachment arm 104 hitting a hard stop in handheld tool 100. Tokeep attachment arm 104 from hitting the hard stop, motion sensors 122and 124 in MTM 120 may use an accelerometer to measure high frequencymotion corresponding to the tremor motion and low frequency motioncorresponding to the tilt motion. MTM 120 (or the controller) may applyleast one of a low pass filter or a high pass filter to distinguishbetween the tremor motion and the tilt motion. In embodiments where ahigh pass filter is used, the position of the attachment arm 104 setpoint may shift in the controller. In one embodiment, the set point isthe location in the attachment arm's 104 range of motion that attachmentarm 104 is trying to get to. The controller/MTM 120 may flip betweencontrolling high frequency (tremor motion) and low frequency (tilt)motion and send instructions to the at least one motion generatingmechanism to oppose the low frequency motion and resist attachment arm104 hitting the hard stop. Alternatively, the controller/MTM 120 maycontrol the tremor motion and tilt motion in parallel. This may includematching the motor (included in the motion generating mechanism)constant to the inertia of the handheld device at high frequencies, andmatching the motor constant to the torque of gravity at low frequencies.

In embodiments where MTM 120 includes both an accelerometer and agyroscope, the accelerometer and the gyroscope may detect an orientationof handheld tool 100 including a pitch of handheld tool 100 and a rollof the handheld tool 100 to resist attachment arm 104 hitting a hardstop. For example, if the handheld tool 100 is rolled to the side, a lowfrequency gain may be applied to the motor to produce the torque equaland opposite to the gravitational vector (cosine of the angle from thezero plane). This low frequency gain is added to any high-frequencytremor correction signals to still produce tremor compensationproperties. The controller may employ at least one of a Kalman filter ora complementary filter, and in response to detecting the tilt motion,the controller may produce torque in the attachment arm 104 equal andopposite to a gravitational vector. Generally, Kalman filters use aniterative two-step process: the first step is a prediction step wherethe filter estimates the current state of variables (here position,velocity, etc. of attachment arm 104); the second step involvesmeasuring the actual state and updating the current state estimationwith a weighted average (with more weight being given to parameters withhigher certainty). A complementary filter is a frequency domain filterusing two or more complementary transfer functions to construct anoise-free signal.

In one embodiment, the handheld tool 100 includes a first motiongenerating mechanism having the first actuator 108, first gear reductionunit 110, and first gearing unit 112. In response to a first set ofvoltage commands from the controller in MTM 120, the first actuator 108drives the first gearing unit 112 through the first gear reduction unit112 to move the attachment arm 104 and the attached implement 102 onpivot 150 in a first degree of freedom 152 relative to the housing 106.Similarly, in response to a second set of voltage commands from thecontroller in MTM 120, the second actuator 130 drives the second gearingunit 134 through the second gear reduction unit 132 to move theattachment arm 104 and the attached implement 102 on pivot 160 in asecond degree of freedom 162 relative to the housing 106. The firstdegree of freedom and the second degree of freedom are different, and inone embodiment, the first and second degrees of freedom areperpendicular to one another (e.g., 90 degrees different from oneanother). In embodiments, the first and/or second motion generatingmechanisms employ gearing units that translate motion to orthogonaldirections relative to the motions generated by their respectiveactuators. Such a translation of motion of the actuators to anorthogonal direction can be achieved through bevel gearing units, suchas those illustrated in FIGS. 1A-1B. Other types of gearing orcombinations of types of gearing, such as work gearing units, a workgearing unit and a bevel gearing unit, etc., capable of translating theactuators' 108 and 130 motions to orthogonal directions can be employedby the handheld tool 100 consistent with the discussion herein. All ofthese configurations may be used to cancel tremor and compensate fortilt motion in accordance with the teachings of the present disclosure.

FIG. 1B illustrates handheld tool 100 of FIG. 1 and further showsattachment/detachment functionality, in accordance with an embodiment ofthe disclosure. As shown, the tool/implement 102 (spoon) is detachablefrom attachment arm 104. In one embodiment the attachment arm 104 andimplement 102 may click together, be held together by magnetic force,screw together, or the like. One skilled in the art will appreciate thatthere are many different ways to attach implement 102 to attachment arm104 to make it easily removable but keep it from falling off during use.This functionality allows the user of handheld tool 100 to use a varietyof implements. In one embodiment, handheld tool 100 may recognize thetype of implement 102 attached to attachment arm 104 and adjust thealgorithms used to stabilize the tool accordingly. Alternatively a usermay annually adjust the stabilization (tremor and tilt) algorithmsdepending on the type of implement 102. For example the user, orhandheld tool 100, may adjust the resistance handheld tool 100 outputsto prevent attachment arm 104 from hitting a hard stop, depending on thetype of implement 102 being used.

FIG. 1C illustrates handheld tool 100 of FIG. 1 along with one exampleof a hard-stop, in accordance with an embodiment of the disclosure. Oneskilled in the art will appreciate that the diagram is highly simplifiedto avoid obscuring certain aspects of the disclosure. As shown,attachment arm 104 has run into bumper 172 which is one example of ahard stop. However, one skilled in the art will appreciate that a hardstop need not necessarily be physical; for example a hard stop may beprogrammed into the device to prevent it from damage. When theattachment arm 104 runs into bumper 172 it causes the attachment arm(and implement 102) to come to an abrupt jolted stop. This may causefood on implement 102 to fly off, or may even cause the user to hurtthemselves if the implement is in the user's mouth. Accordingly, it isdesirable for handheld tool 100 to resist hitting the hard stop, andensure that a gradual increase in resistance is applied to attachmentarm 104 prior to it reaching the hard stop. This resistance may beapplied by motion generating mechanism 174. It is worth noting thathandheld tool 100 may still occasionally hit the hard stop if enoughforce is applied to attachment arm 104 (as depicted); however, handheldtool 100 will resist this motion and will also resist tilting motionswhich may otherwise result in attachment arm 104 hitting the hard stop.

In the depicted embodiment MTM 120 includes at least one gyroscope 199located in the distal end of attachment arm 104. It is worth noting thatalthough gyroscope is located outside of the boundaries of the MTM 120block, any device used for measuring motion may be considered “included”in MTM 120 regardless of its location in handheld tool 100. Moreover, inone or more embodiments, MTM 120 may include a commercially available orproprietary internal measurement unit (IMU).

FIGS. 2A-2C illustrate a variety of handheld tool attachments, inaccordance with several embodiments of the disclosure. One skilled inthe art will appreciate that the tool attachments depicted are notexhaustive and that other tool attachments may be used.

FIG. 2A shows toothbrush attachment 202A that is compatible with thehandheld tool (e.g., handheld tool 100) of FIG. 1A. The toothbrush mayallow a person with tremor to brush their teeth without injuring theinterior of their mouth by inadvertently jamming the toothbrush intotheir teeth/gums. Toothbrush attachment 202A may be preferably used witha handheld tool that resists contacting hard stops. Because somepressure is necessarily applied to toothbrush tool 202A, the deviceshould resist hitting a hard stop to keep the user from injuringthemselves.

FIG. 2B illustrates fork attachment 202B. Similar to toothbrushattachment 202A, it may be advantageous to use the fork in conjunctionwith a handheld tool that has hard stop resistance; this keeps the userfrom inadvertently injuring themselves by having the movement of theattachment arm max out

FIG. 2C depicts paintbrush attachment 202C. Although encountering a hardstop with a paintbrush attachment poses little risk for the user of thehandheld tool, a hard stop may result in a painting that has abrupttransitions between lines and lacks aesthetic appeal. Accordingly, itmay be advantageous to use paintbrush attachment 202C with a handheldtool that resists the effects of hard stops.

It is worth noting that the devices depicted here may all have their ownspecific tremor reduction and hard stop resistance hardware andalgorithms. For instance, when using toothbrush attachment 202A,intricacy of movement may be less important than the ability to exertforce. Accordingly, the resistance the attachment arm outputs tocounteract encountering a hard stop may be relatively large. Conversely,in the case of paintbrush attachment 202C intricacy of movement may beprized over the force needed to effectively use the attachment.Accordingly, the handheld device may resist hitting the hard stop lesswith paintbrush attachment 202C than with toothbrush attachment 202A andfork attachment 202B.

FIG. 3 is a flowchart illustrating a method 300 of tremor stabilizationand hard stop resistance, in accordance with several embodiments of thedisclosure. The order in which some or all of process blocks 301-305appear in method 300 should not be deemed limiting. Rather, one ofordinary skill in the art having the benefit of the present disclosurewill understand that some of method 300 may be executed in a variety oforders not illustrated, or even in parallel.

Block 301 illustrates measuring a tremor motion and a tilt motion with amotion tracking module (“MTM”) disposed in a housing of the handhelddevice (e.g., handheld tool 100 of FIG. 1). Measuring the tremor motionand the tilt motion may include separating high frequency motioncorresponding to the tremor motion from low frequency motioncorresponding to the tilt motion and in response. In one embodiment, thetremor motion and the tilt motion may both be measured by anaccelerometer, and at least one of a low pass filter or a high passfilter is used to distinguish between the tremor motion and the tiltmotion. In another embodiment, measuring the tremor motion and the tiltmotion includes using an accelerometer and a gyroscope included in theMTM, and the tremor motion and the tilt motion are separated using atleast one of a Kalman filter or a complementary filter.

Block 303 illustrates moving the attachment arm to reduce tremor in theattachment arm. In one embodiment, the at least one motion generatingmechanism included in the handheld device has a motor, and the motoroutput is adjusted to counteract the inertia of the housing using theattachment arm. This reduces the effect of the user's tremor in theattachment arm, and stabilizes the location of the distal end of theattachment arm.

Block 305 shows the handheld device resisting the attachment arm hittinga hard stop in response to measuring a tilt motion. As discussed above,the “hard stop” is a maximum movement distance in one direction; thismay be either a physical limit or a limit built into software (e.g., amovement limit programmed into the device to prevent damage to thedevice).

In one embodiment, a motion generating mechanism disposed in thehandheld tool resists the attachment arm hitting the hard stop inresponse to measuring the low frequency motion and shifting a set pointof the attachment arm using the controller. In other words, the handleddevice shifts the location of the position that the attachment arm istrying to reach, when the handheld device realizes the attachment arm istoo close to a hard stop. Further, resisting the attachment arm hittingthe hard stop may include includes adjusting a motor output tocounteract a torque of gravity resulting from the tilt motion. Forexample if the attachment arm starts to tilt and fall, the handhelddevice may detect this motion with an accelerometer/gyroscope and outputa torque to counteract the fall. The torque may be equal and opposite tothe gravitational vector.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (“ASIC”) orotherwise.

A tangible non-transitory machine-readable storage medium includes anymechanism that provides (i.e., stores) information in a form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. A method of tremor reduction in a handhelddevice, comprising: measuring a tremor motion and a tilt motion with amotion tracking module (“MTM”) disposed in a housing of the handhelddevice; in response to measuring the tremor motion, moving an attachmentarm with at least one motion generating mechanism to reduce the tremormotion in the attachment arm; and in response to measuring the tiltmotion, moving the attachment arm with the at least one motiongenerating mechanism to resist the attachment arm from hitting a hardstop in the handheld device, wherein the hard stop is an outermost pointin a range of motion of the attachment arm.
 2. The method of claim 1,wherein measuring the tremor motion and the tilt motion includesseparating high frequency motion corresponding to the tremor motion fromlow frequency motion corresponding to the tilt motion, and in responseto measuring the low frequency motion resisting the attachment armhitting the hard stop, wherein the hard stop is a maximum movementdistance in one direction.
 3. The method of claim 2, wherein measuringthe tremor motion and the tilt motion includes: measuring the tremormotion with a motion sensor; measuring the tilt motion with the motionsensor; and using at least one of a low pass filter or a high passfilter to distinguish between the tremor motion and the tilt motion, andwherein the at least one motion generating mechanism resists theattachment arm hitting the hard stop in response to measuring the lowfrequency motion and shifting a set point of the attachment arm.
 4. Themethod of claim 3, wherein the at least one motion generating mechanismincludes a motor, and wherein reducing the tremor motion in theattachment arm includes adjusting a motor output to counteract aninertia of the housing, and wherein resisting the attachment arm hittingthe hard stop includes adjusting the motor output to counteract a torqueof gravity resulting from the tilt motion.
 5. The method of claim 2,wherein measuring the tremor motion and the tilt motion includes using amotion sensor and a gyroscope included in the MTM.
 6. The method ofclaim 5, wherein measuring the tremor motion and the tilt motionincludes using at least one of a Kalman filter or a complementaryfilter.
 7. The method of claim 5, wherein the at least one motiongenerating mechanism includes a motor, and wherein in response todetecting the tilt motion with the motion sensor and the gyroscope, themotor outputs a torque equal and opposite to a gravitational vector toresist the attachment arm hitting the hard stop.
 8. A non-transitorymachine-readable storage medium having instructions stored thereon,which when executed by a processing system, cause the processing systemto perform a method comprising: measuring a tremor motion and a tiltmotion of a handheld device with a motion tracking module (“MTM”); inresponse to measuring the tremor motion, controlling an attachment armwith at least one motion generating mechanism to reduce the tremormotion in the attachment arm, wherein the at least one motion generatingmechanism is coupled to the attachment arm included in the handhelddevice; and in response to measuring the tilt motion, controlling theattachment arm with the at least one motion generating mechanism toresist the attachment arm from hitting a hard stop.
 9. Thenon-transitory machine-readable storage medium of claim 8, whereinmeasuring the tremor motion and the tilt motion includes: measuring highfrequency motion corresponding to the tremor motion with a motion sensorincluded in the MTM; measuring low frequency motion corresponding to thetilt motion with the motion sensor; and using at least one of a low passfilter or a high pass filter to distinguish between the tremor motionand the tilt motion.
 10. The non-transitory machine-readable storagemedium of claim 9, wherein resisting the attachment arm hitting the hardstop includes adjusting an output from a motor in the at least onemotion generating mechanism to counteract a torque of gravity resultingfrom the tilt motion.
 11. The non-transitory machine-readable storagemedium of claim 8, wherein measuring the tremor motion and the tiltmotion of the handheld device includes using a motion sensor and agyroscope included in the MTM.
 12. The non-transitory machine-readablestorage medium of claim 11, wherein in response to measuring the tiltmotion with the motion sensor and the gyroscope, a motor in the at leastone motion generating mechanism produces a torque equal and opposite toa gravitational vector.
 13. A handheld tool, comprising: a housing; atleast one motion generating mechanism disposed within the housing; anattachment arm coupled to the at least one motion generating mechanism;a motion tracking module (“MTM”) disposed in the housing to detectmotion of the housing; and a controller electrically coupled to the MTM,wherein the controller includes logic that when executed by thecontroller causes the handheld tool to perform operations including: inresponse to the MTM detecting a tremor motion, controlling the at leastone motion generating mechanism to move the attachment arm relative tothe housing to reduce the tremor motion in the attachment arm; and inresponse to the MTM detecting a tilt motion, controlling the at leastone motion generating mechanism to resist the attachment arm fromhitting a hard stop in the handheld tool, wherein the hard stop is anoutermost point in a range of motion of the attachment arm.
 14. Thehandheld tool of claim 13, wherein the MTM includes a motion sensor tomeasure high frequency motion corresponding to the tremor motion and lowfrequency motion corresponding to the tilt motion, wherein thecontroller further includes logic that when executed by the controllercauses the handheld tool to perform operations including: applying atleast one of a low pass filter or a high pass filter to distinguishbetween the tremor motion and the tilt motion; and sending instructionsto the at least one motion generating mechanism to oppose the lowfrequency motion and resist the attachment arm hitting the hard stop.15. The handheld tool of claim 14, wherein the at least one motiongenerating mechanism includes a motor, and wherein the controllerincludes logic that when executed by the controller causes the handheldtool to perform operations including: reducing the tremor motion in theattachment arm by adjusting the motor output to counteract an inertia ofthe housing, and resisting the attachment arm hitting the hard stop byadjusting the motor output to counteract a torque of gravity resultingfrom the tilt motion.
 16. The handheld tool of claim 13, wherein the MTMincludes a motion sensor and a gyroscope, wherein the motion sensor andthe gyroscope detect an orientation of the handheld tool including apitch of the handheld tool and a roll of the handheld tool to resist theattachment arm hitting the hard stop.
 17. The handheld tool of claim 16,wherein the controller includes logic that when executed by thecontroller causes the handheld tool to perform operations including:using at least one of a Kalman filter or a complementary filter toreduce the tremor motion in the attachment arm and resist the attachmentarm hitting the hard stop.
 18. The handheld tool of claim 16, whereinthe at least one motion generating mechanism includes a motor, andwherein the controller includes logic that when executed by thecontroller causes the handheld tool to perform operations including: inresponse to detecting the tilt motion, instructing the motor to producetorque equal and opposite to a gravitational vector to resist theattachment arm hitting the hard stop.
 19. The handheld tool of claim 13,wherein the MTM includes at least one gyroscope, and the at least onegyroscope is located in at least one of a distal end of attachment armor in the housing.
 20. The handheld tool of claim 13, wherein the MTMincludes an internal measurement unit (IMU).
 21. The handheld tool ofclaim 13, wherein the attachment arm is configured to receive at leastone of a spoon attachment, a fork attachment, a toothbrush attachment,or a paintbrush attachment.